Process of tbeating bagasse for fiber-making purposes



description of the invention, such Patented Feb. 23, 1926.

UNITED STATES TREADWAY B. MUNROE, 0F FOR-EST GLEN, MARYLAND.-

PROCESS-0F TREATING BAGASSE FOR FIBER-MAKINGIPURPOSES.

No Drawing. Application filed J'u1y7,

To all whom it may concern:

Be it known that l, TREADWAY ll. MUN- ROE, a citizen of the UnitedStates, residing at Forest Glen, in the county of Montgomery and Stateof Maryland, have invented certain new and useful Improvements inProcesses of Treating Bagasse for Fiber- Making' Purposes; and I dohereby declare the following to be a full, clear, and exact as willenable others skilled in the art-to which it appertains to make and usethe same.

This invention relates to a process of treating bagasse for fiber makingpurposes and especially adapted for the purpose of making fiber boards.It has for its object to provide a procedure which will be moreefficient in action and less costly to carry out than those heretoforeproposed.

With these and other objects in view, the invention consists in thenovel steps and combinations of steps constituting the process, all aswill be more fully hereinafter disclosed and particularly pointed out inthe claims.

In order that the precise invention may be the more clearly understood,it is said As is Well known, when bagasse fibers are subjected to acooking action in the presence of chemicals to make fiber boards, theyare often found to be extremely harsh, hard to cook, hard to refine inthe Clallin machines and they do not constitute a product as soft andpliable as-is desired.

According to this invention on the other hand, it is found that if thefibers are subjected to a fermenting action before they are cooked, theywill be so loosened from the cementing material which holds theindividual fibers together that said fibers will be so soft and pliablethat very small quantities of chemicals will be needed to cook the same,and in many cases no chemicals at all -Will be required in the cookingprocess.

It is further well known that when the chemically cooked fibers ofbagasse are madeup into a fiber board, there is considerable difficultyoften experienced in uniformly drying and draining the same. That is tosay, the drying and draining of-these fibers is found to be so uneventhat the board is liable to curl up and to not be in such a smooth flatcondition, as is desired for a commercially successful board. But,again,

according to this invention, it is found that if the fibers arefermented as above men- 1924. Serial N0. 724,712.

' tioned so as to render them soft and yielding and if they are ,thencooked in water with either a very small quantity of chemicals or withnone at all, and if they are mixed with a suitable preccntagc of woodul) orw round 11) news )a )er material either bcforc'or after cookingbut preferably should be comparatively inexpensive and very certain inresults or else the cost of a.

satisfactory product will be prohibitive.

I overcome the cost problem by proceeding as follows It is well knownthat bagasse as it comes from the sugar mills in addition to containingsay 50% of moisture, also contains from 3% to 4% of sugar and othersubstances which cause the bagasse to undergo fermentations and decayifthese actions are not properly controlled. \Vhile it is true if thebagasse is dried at the mill it will escape these fermentations, yet itis further well known that such drying is commercially too'expensive tobe practicable.

Therefore, in proceeding according to this invention, the bagasse isbaled at the mill, it is shipped to the place of use, and

these bales are placed in piles on well dried ground,in such manner thata minimum of surface will be exposed to the weather and sufficientventilation between the bales will be provided to permit moisture,vapors and gases to freely escape. It is found to be sufficient, ifthebales are piled fiat on the ground in a rectangular layer, with a fewinches of space separating the sides and ends of the bales. Then, on topof this layer another similar layer is piled, each bale of the "secondlayer breaking joint with the bales underneath and likewise separated bya few inches from each other. The upper or second layer is made of aless area than the bottom layer, so that 'a stepped or pyramid formationis started by disposing of the outer bales of the second layer, wellinside the outer bales of the lower layer. This form of piling iscontinued, each upper layer being of a less area than the next lowerlayer, each bale breaking joint with the vents or passages between thelower bales, and each bale in a layer being separated on its sides andends from an adjacent bale.

that the fibers are soft and silky to the touch and their strengthisunimpaired. If

this fermentation is allowed to proceed, unprotected from the weatherthe fiber itself will be injured so it is found tobe desirable to'open'up a few of the fermented bales, and spread a layer of bagasse 6 or8 inches thick over the entire pile of bales. After this is done, thepile of bales may be allowed to age for a period of from a month to ayear, during which time the fe nented bagasse may be freely used forfiber m king purposes.

Bales from these piles are broken open and loosened out the fibersseparated and fed to a cooker in which they may be subjected to theaction of hot water alone for a period of from 45 minutes to two andone-half hours. While it is well known that bagasse fibers may be cookedwith alkalies and other suitable chemicals, such cooking has a disfrom10% to 50%.

advantage that it dissolves valuable constituents and that due to theaction of hydration of the fiber and the production of oxycellulose andother products, the fiber is hard to handle in all pulp formingequipments. By softening the fermented fiber with hydrolysis in hotwater on the other hand, the cementitious material is removed frombetween the fibers rendering them in a suitable condition for refiningby well known machines such as Claflins, etc., without the disadvantagesexperienced when such fibers are cooked with caustic or other chemicals.4

It is found, however, that cooking fibers with chemicals and hot water,or even without chemicals, as described above does not produce fiberswith all the properties desired in the manufacture of aheat insulatingboard,

for the fibers are rather long and coarse and produce a board that doesnot have a good surface and one which it is difiicult to waterproof.These objections, however, are overcome in this invention by adding tosuch bagasse fibers, other fibers in a proportion Such fibers arepreferably ground wood, waste newspapers, or fibers that are classed bypaper makers as close stock, also what s known as wood pulp tailings aresatisfactoryfor'this purpose. These fibers are preferably employed byadding them to the fermented bagasse as it goes into the cooker, for inaddition to their becoming well mixed with the bagasse fibers, thesesaid other fibers are .the products of hydrolysis by the water presentbeing drained from the fiber and replaced with fresh water two or threetimes, or until the mixture of fibers are practically free from thesubstances dissolved from the hot water. The mixed fibers are then readyfor refining, and maybe pumped to a Claflin or other suitable refiningequipment, and refined into a mixture of fibers suitable for the purposedesired. At this point may be added any suitable Waterproofing materialand a fireproofing material may be applied at any suitable time later.

In the manufacture of heat insulating boards, this mixture of bagasseand other. fibers with water in the proportion of onetenth to one percent of fibers with ninetynine and nine-tenths to ninety-nine per-centwater, is fed into a continuous board forming machine, such as thatdisclosed in U. S. Patent #1,456,608, where it is formed into a wetboard containing 25% to 40% fiber and 7 5% to water. It is now necessaryto remove this moisture from the board and this is accomplished bysubjecting the wet board to the action of from 250 1*. to 350 F. of heatin any suitable continuous steam.

heated drier, for a period of from one to three hours to reduce themoisture content from 60% or down to less than 5%. It is found that thewood pulp or other close fibers added to the board are particularlyvaluable'at this point of the procedure for bagasse fibers are what isknown as free stock, that is, they do not hold on to their watertenaciously but give it up rather fre' while wood or similar fibersbeing what is known as close stock do not give up their moisture freely.The result is it is found that in the drier, these wood or similarfibers which are mixed with the bagasse the temperature of'250 F. to 350F. from.

scorching the surface of the board as it becomes progressively drier.This humidity will also prevent the board becoming dry so moisturecanquick on the surface that the not come from the interior to saidsurface. When this fiber board isdry, it is a'good heat insulator and isquite water resisting,

' so therefore if a layer on the surface becomes dry before the moisturehas been removed ely under the influence of heat,.

from the interior of the board, it will be seen that this surface layerwill act as a heat insulator preventing the penetrating of the heat tothe interior, and will therefore reduce the moisture coming from theinterior. It is also found that this addition of close fibers to thebagasse fibers, assists materially in the production of aboard thatissues from the drier absolutely fiat and smooth and with no tendency towarp or curl.

This most desirable result is assisted by cooking fermented fibers withhot water rather than with chemicals, because when ordinary bagassefibers are cooked with chemicals and subjected to heat it is found theyundergo considerable shrinkage in length. Such fibers made into boards,and subjected to heat, of course, set up uncontrollable strains indrying that cause the boards to curl. The close fibers by controllingthe extraction of the moisture from the bagasse fibers also control thisshrinkage of the bagasse fibers because they control the time that theselong fibers must be subjected to the heat in order to manufacture theboard. It is also found that these close wood fibers fill in between thebagasse fibers, thus creating minute air spaces instead of larger airspaces, and they fill up particularlv the interstices on the surface ofthe finished fiber board thus rendering it more ornamental.

hat is claimed is 1. The process of preparing bagasse for pulp makingpurposes which consists in disposing said'bagasse in piles havingventilating channels for the escape of gases and vapors; subjecting saidpiled bagasse to a fatty acid fermentation to loosen the fibers presentfrom their incrusting materials; covering said piled bagasse topartially protect it from the weather before the strength of the fibersis impaired; mixing said fibers with other fibers which give up theirmoisture less freely than do bagasse-fibers; cooking said fermentedfibers; and refiningthe cooked fibers. 1

2. The process of preparing begasse for pulp making purposes whichconsists in subjecting said bagasse to an acetic acid fermentation;stopping said fermentation before the strength of the fibersis impaired;mixing the fermented bagasse with fibers derived from wood; subjectingthe mixture to a cooking'action; and refining the cooked mixture offibers.

3. The process of making a heat insulating board from bagasse whichincludes in subjecting said bagasse to a fermentin ac tion; stoppingsaid action after the fibers present have been loosened from theocmentitious material binding the same and before the strength of saidfibers has been impaired; mixing said fermented bagasse with woodfibers; subjecting the mixture of fibers thus produced to a boilingaction; subjecting the mixture to a refining action; forming the refinedmixture into a board; and drying said board.

4. The process of preparing bagasse for pulp making purposes whichconsists in baling said bagasse; disposing said baled bagasse in pileshaving ventilating channels for the escape of gases and vapors;subjecting said piled bagasse to a fatty acid fermentation to loosen thefibers present from their incrusting materials; covering said piled andbaled bagasse to partially protect it from the weather before thestrength of the fibers is impaired; cooking said fermented fibers withhot water containing no added chemicals; mixing said fibers with otherfibers which give up their moisture less freely than do bagasse fibers;and refining the cooked fibers. I

5. The process of preparing bagasse for pulp making purposes whichconsists in subjecting said bagasse to an acetic acid fermentation;stopping said fermentation before the strength of the fibers isimpaired; mixing the fermented bagasse with more than 3% of fibersderived from wood; subjecting the mixture to a cooking action in waterto which no chemicals have been added; and refining the cooked mixtureof fibers.

6. The process of making a heat insulating board from bagasse whichincludes subjecting said bagasse to a fermenting action; stopping saidaction after the fibers present have been loosened from the cementitiousmaterial binding the same and before the strength of said fibers hasbeen impaired; mixing said fermented bagasse with more than 3% of woodfibers; subjecting the mixture of fibers to a boiling action; subjectingthe mixture to a refining action; forming the refined mixture into aboard; and drying said board in an atmosphere containing suflicientmoisture to prevent scorching the board..

7 The process of making a heat insulating fiber board which consists insubjecting piled bagasse to an acetic acid fermentation until the fiberspresent are partially loosened from the bundles in which they naturallyoccur; stopping said fermentation before the strength of the fibers isimpaired; mixing with the fermented bagasse a sufficient quan tity offibers derived from wood to aid in drying the formed board; subjectingthe mixture thus obtained to a cooking action; refining the cookedmixture of fibers; separating from the refined mixture thus obtained anyobjectionable constituents derived from the cooking action; adding afire re-- sis'ting material to said mixture; and forming the mass thusobtained into a board.

8. The process of making a heat insulat- "ing fiber board which consistsin subjecting piled bagasse to an acetic acid fermentation until thefibers present are partially loosened from the bundles in which theynaturally occur; stopping said fermentation before the strength of thefibers is impaired; mixing with the fermented bagasse a sufiicientquantity of ground fibers derived from Wood to aid in drying the formedboard; subjecting the mixture thus obtained to a cooking action in waterdevoid of chemicals; refining the cooked mixture of fibers; separatingfrom the refined mixture thus obtained any objectionable constituentsderived from the cooking action; forming the mass thus obtained into aboard; and drying said board in a moist atmosphere.

9. The process of making a heat insulating fiber board, which consistsin mixing fermented bagasse, fibers with wood fibers; cooking themixture in water; refining the cooked mixture; forming a board from therefined mixture; and drying said board.

10. The process of making a heat insulating fiber board which consistsin mixing fermented bagasse fibers with wood fibers; cooking the mixturein water; refining the cooked mixture; adding a waterproofing materialto the refined fibers thus produced; forming a board from the refinedand waterproofed mixture; and drying said board.

11. The process of making a heat insulating fiber board, which consistsin mixing fermented bagasse fibers with wood fibers; cooking the mixturein water; refining the cooked mixture; adding a waterproofing materialto the refined fibers thus produced; forming a board from the refinedmixture; drying said board; and fireproofing said board.

In testimony whereof I affix my signature.

' TREADWAY B. MUNRQE.

